[unreadable] We propose to develop an x-ray microtomography system specifically designed for nondestructive 3D imaging of orthopedic implant coatings to investigate fracture mechanics for the purpose of improving the implant technology. The proposed x-ray microtomography system offers unique advantages over visible-light and electron microscope based methods for nondestructive 3D imaging of orthopedic implants in the study of fracture mechanics and development of advanced coating materials. Specifically it would allow 80nm-resolution studies of subsurface cracks in situ in an unperturbed state without the need of cutting the sample to risk altering the crack. It would also allow the cracks to be seen in or through any material regardless of optical transparency (such as simulated body fluid) and would enable the same crack to be imaged repeatedly to monitor its progress. The hard x-ray microscope will have much wider usage for fracture mechanics studies of other types of implant coatings, such as commercial hydroxyapatite, and nondestructive imaging of internal structures in any solid materials. [unreadable] [unreadable]